Luminescence, optical absorption and electron spin resonance of an X-irradiated poly(ester urethane)

X-ray-induced damage in Estane® 5703, a segmented poly(ester urethane) copolymer, has been investigated by thermally stimulated luminescence, radioluminescence, optical absorption and electron spin resonance techniques over a wide temperature range. Some glow curve features correlate with molecular motion of the polymer, as determined by viscoelastic measurements, indicating charge detrapping via thermal destruction of cavity traps. Spectral emission consists of four Lorentzian bands with maxima at 2.38, 2.55, 2.74 and 2.93 eV, which are attributed to triplet-to-singlet (π, π∗) electronic transitions of the phenyl group in the polymer hard segment. Absorption peaks at 3.97, 4.29 and 4.46 eV are also assigned to (π, π∗) transitions of the phenyl group. Several radicals with overlapping resonances are induced at low temperature, which, with increasing temperature, evolve into the relatively stable peroxy radical at room temperature.